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Practical guides on LLM cost optimization, model routing, and AI infrastructure.

·8 min read

Hardcoding a Cheaper AI Model Per Step: What Goes Wrong

You can hardcode a cheaper model per app step, but four problems erode the savings: quality drops, model retirements, version drift and missed newer models.

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·Updated October 7, 2026·7 min read

Best LLM for Coding in 2026

A routing-first guide to the best LLM for coding in 2026. Which coding tasks go to which model, cost per task type, and SWE-bench benchmark scores compared.

best llm for codingcoding llmswe-benchmodel routingllm cost optimization
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·Updated October 15, 2026·8 min read

DeepSeek V4 Pro API Pricing: Peak and Off-Peak Rates

DeepSeek V4 Pro costs $1.32/$3.96 per million tokens at peak and $0.66/$1.98 off-peak. Prices, limits and status checked 2026-10-15, with monthly math.

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·Updated October 7, 2026·8 min read

GLM-5.1 Leads SWE-Bench Pro at One-Fifth the Price

GLM-5.1 scored 58.4 on SWE-Bench Pro, beating GPT-5.4 and Claude Opus 4.6, at $0.95 per million input tokens. The coding routing default just changed.

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·Updated October 15, 2026·14 min read

GPT-5.4 vs GPT-5.4 mini: Routing Math After GPT-6

GPT-5.4 mini costs 70% less per token than GPT-5.4. October 2026 prices, worked cost math, and the same routing choice with GPT-6 and GPT-5.6 models.

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·Updated October 16, 2026·26 min read

OpenAI API Cost Too High? Six Fixes, Ordered by Effort

How to reduce OpenAI API costs: a 9-step checklist and six fixes, from model choice and caching to Flex, Batch and reasoning effort, with October 2026 prices.

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·Updated October 16, 2026·9 min read

o3 vs o3-mini: Costs, Shutdown Dates and What to Use Now

o3-mini shuts down Oct 23, 2026 and o3 on Dec 11. Per-request costs with reasoning tokens, GPT-6 prices and effort levels, and how to test a switch.

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·Updated October 20, 2026·16 min read

AI Cost Per User: Formula, Examples and SaaS Margins

How to calculate AI cost per user and its share of plan price, with GPT-6 and Claude examples, reasoning tokens, caching and a $29 plan. Checked Oct 20, 2026.

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·Updated October 20, 2026·19 min read

Claude API Pricing: What 1K to 1M Tokens Cost (Oct 2026)

What 1,000, 100,000 and 1 million Claude tokens cost in October 2026, for Haiku 5.5, Sonnet 5.5, Opus 5.5 and Fable 5.1, plus caching, batch and worked examples.

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·Updated October 14, 2026·14 min read

Claude Haiku vs GPT-4o-mini and GPT-6 Luna (October 2026)

Claude Haiku 5.5 and GPT-6 Luna both list $0.10 input and $0.50 output per million tokens. Where the real costs differ, plus Haiku 4.5 vs GPT-4o-mini today.

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·Updated October 15, 2026·8 min read

Gemini 2.5 Pro vs Flash Cost (and the Newer Gemini Models)

Gemini 2.5 Flash costs about a quarter of 2.5 Pro per token. Prices, worked examples, when Pro pays off, and the newer models Google offers new projects.

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·Updated October 15, 2026·8 min read

Six Ways to Send Fewer LLM Tokens Without Losing Quality

Six techniques, from prompt compression to output length control, that can take a typical 4,500-token prompt to about 2,100 tokens. Here is how to apply them.

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·Updated October 8, 2026·8 min read

The Multi-Agent Cost Spiral: Why Agent Loops Cost So Much

Every step in an agent loop compounds token count. A 20-step agent can cost 50x more than a single call. Here is the math and how to design agents on budget.

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·Updated October 15, 2026·9 min read

The Hidden Costs in Your RAG Pipeline (And How to Cut Them)

Retrieved context alone can cost $12,000 a month at 100,000 RAG calls a day. The four real cost centers, how to filter passages, and what each step costs.

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·Updated October 15, 2026·9 min read

How to Reduce Claude API Costs: A Practical 5-Step Guide

A team spending $5,000 a month on Claude can get to about $2,240 without changing what its product does, and lower by moving simple tasks to Haiku 5.5.

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·Updated October 15, 2026·7 min read

How to Reduce OpenAI Embedding Costs at Scale

Embedding costs are the most overlooked line item in AI infrastructure. Even cheap models add up at scale. Five techniques we estimate cut costs 50-80%.

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·Updated October 9, 2026·7 min read

How to Budget for AI API Costs at a Startup

Most founding teams underestimate AI API costs by 5-10x in year one. Here are the rules of thumb, scale projections, and budget mistakes that will cost you.

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·Updated October 16, 2026·6 min read

PromptUnit vs AWS Bedrock: Platform vs Cost Optimization

AWS Bedrock is a managed AI platform inside AWS. PromptUnit cuts your LLM costs per request with two settings and no SDK change. Different tools and jobs.

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·Updated October 15, 2026·5 min read

PromptUnit vs Helicone: Cost Optimization vs Observability

Helicone logs and explains LLM calls; it has been in maintenance mode since Mintlify acquired it in March 2026. PromptUnit cuts the cost of each request.

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·Updated October 15, 2026·5 min read

PromptUnit vs Langfuse: LLM Tracing vs Cost Optimization

Langfuse is an open-source LLM tracing and evaluation platform. PromptUnit cuts the cost of each request. They do different jobs and often work together.

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·Updated October 15, 2026·5 min read

PromptUnit vs LangSmith: Evaluation vs Cost Optimization

LangSmith is LangChain's platform for tracing, evaluating and debugging LLM apps. PromptUnit cuts the cost of each request. Different jobs, often used together.

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·Updated October 15, 2026·5 min read

PromptUnit vs Portkey: Same Category, Different Priorities

Portkey and PromptUnit both sit between your app and AI providers. Portkey gives you control: rules, fallback, logs. PromptUnit cuts the cost of each request.

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·Updated October 15, 2026·8 min read

Embedding Model Routing in 2026: A 6x Cost Spread

OpenAI at $0.02/M, Voyage 4 at $0.06/M, Cohere Embed 5 at $0.08 to $0.12/M. How to route embedding calls by workload to match cost to quality.

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·Updated October 19, 2026·6 min read

Claude Haiku 5.5 vs Sonnet 5.5: Cost and Routing Guide

Claude Haiku 5.5 costs $0.10/$0.50 per million tokens, Sonnet 5.5 $2/$10. When Haiku is enough, what changes in the API, and a worked routing example.

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·Updated October 16, 2026·18 min read

LLM Cost Tracking: Per Request, Feature and User (2026)

LLM cost tracking per request, feature and user: a cost function with cached tokens, per-user SQL, provider spend caps and a tools table checked Oct 16, 2026.

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·Updated October 15, 2026·7 min read

OpenRouter vs LiteLLM, and Where PromptUnit Fits

OpenRouter puts hundreds of models behind one key. LiteLLM is a gateway you run yourself. PromptUnit cuts cost per request and runs on your own OpenRouter key.

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·Updated October 7, 2026·4 min read

Catch expensive AI model usage in every pull request

The PromptUnit GitHub Action scans your PR diff for expensive models like GPT-4o and Claude Opus, then posts routing savings estimates before the code merges.

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·Updated October 9, 2026·10 min read

Function Calling: Why Agent Loops Bill 5x Your Estimate

Tool use resends definitions on every turn and re-includes results in context. Agent loops compound the cost, and token bills run 3-5x over projections.

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·Updated October 7, 2026·9 min read

Batch API Is 50% Off Every Major Provider. What to Move?

OpenAI, Anthropic, Google, and Groq offer 50% off batch processing for async workloads. Stack it with caching for 75-95% savings. Which tasks can wait?

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·Updated October 7, 2026·8 min read

Gemma 4 31B: Self-Host vs API Routing Math

Gemma 4 31B hits 89.2% AIME at 855 t/s on one H100, under Apache 2.0. The self-hosting break-even against API providers just dropped. Here is the math.

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·Updated October 15, 2026·8 min read

GPT-5.5 Takes Text and Images, Not Audio or Video

GPT-5.5 reads text and images and writes text. Audio and video need other models. See per-hour audio prices and a worked example you can recompute.

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·Updated October 8, 2026·7 min read

Groq for LLM Routing: Speed, Price and When to Use It

Groq serves OpenAI's open GPT OSS models at up to about 1,000 tokens per second, from $0.075 per million input tokens. Which workloads to move, with real math.

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·Updated October 7, 2026·10 min read

What We Measured Routing GPT-4o Traffic to Cheaper Models

Early first-party data from PromptUnit's own tests: how often a cheaper model matched the one the app chose in 24 comparisons, what it cost, and the limits.

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·Updated October 15, 2026·7 min read

The Hidden Cost of Defaulting to Your Flagship Model

What defaulting to your flagship model costs beyond the invoice: waiting in dollars, real OpenAI rate limits and model retirements. Checked 2026-10-15.

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·Updated October 15, 2026·25 min read

LLM Routing: How It Works, Strategies and Real Data

LLM routing sends each request to the cheapest model that can answer it well. Six strategies, what RouterBench and RouteLLM found, and our own data.

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